To participate in such fashion, Smith first received medical clearance from an independent neurologist for a concussion that knocked Smith from Sunday's 24-24 tie with the St. Louis Rams.

Smith's appearance on the practice field bodes well for his availability in Monday night's NFC showdown between the host 49ers

(6-2-1) and Chicago Bears (7-2).

The Bears also are dealing with the NFL-mandated, post-concussion process for their quarterback, Jay Cutler, who left Sunday night's loss to the Houston Texans with a second-quarter concussion.

The Bears did not practice Wednesday and Cutler's availability is more suspect than Smith's, considering Cutler missed a game last season with a concussion.

Smith headed to the locker room before halftime Sunday after reporting blurred vision in the second quarter. Coach Jim Harbaugh said Smith complained of the vision problem after converting on a fourth-and-1 dive, which kept alive a series that Smith capped with a 14-yard touchdown pass to Michael Crabtree.

The 49ers will hold full practices Thursday through Saturday before a light walk-through session Sunday, leaving Smith ample time to participate fully in practice.

During Wednesday's 20-minute access period for the media, Smith looked as he does at every practice, aside from the black jersey. He wore his gold helmet, a play-calling wristband on his left forearm, a short towel off his right hip, red shorts and not-so-fashionable white socks with black cleats.

Smith did not miss any practice time with his last documented concussion, that coming after last season's home opener against the Dallas Cowboys.

Left tackle Joe Staley and reserve guard Daniel Kilgore, the only other 49ers to suffer concussions this season, did miss the ensuing game following their respective concussion last month.

All the 49ers' other key players appeared to practice Wednesday, including several who sustained injuries Sunday: running back Frank Gore (hand, ribs), guard Mike Iupati (knee) and linebacker Aldon Smith (hand/wrist).

* Linebacker Aldon Smith (9 ? sacks) is on the verge of becoming the first 49er since Chris Doleman in 1997-98 to post back-to-back seasons of at least 10 sacks.

* Four 49ers are leading their respective positions in NFC Pro Bowl voting at NFL.com: linebacker Patrick Willis, guard Mike Iupati, kicker David Akers and special-teams candidate C.J. Spillman. None are among the league's top 10 vote getters. Willis is on pace for his sixth Pro Bowl trip in as many seasons, and Akers made last season's team. Iupati and Spillman are bidding for their first Pro Bowl berths.